This invention relates to cranes and, more specifically, to a parasitic crane which attaches to a vehicle and uses the weight of the vehicle to stabilize it against tipping when holding a load.
Various cranes have heretofore been used for loading and unloading vehicles or otherwise moving loads. Although such cranes are generally useful, they have usually been subject to one or more of several disadvantages.
Prior art cranes are often quite heavy, the weight being used to stabilize the crane and allow it to lift relatively heavy loads. Such heavy cranes are difficult to transport from one location to another and often must include their own power plant for moving the base of the crane. Cranes are often difficult to position quickly and efficiently, especially when other vehicles are quite close. Some cranes are limited to moving loads from a given starting point to a given unloading point along a fixed path and are quite efficient at moving loads along the path. However, the limitation of such cranes to the given load movement path requires the movement of loads to the starting point before the crane can lift them. On the other hand, cranes which are not as limited in their load movement paths are often slower at moving loads than the fixed path type of cranes.
Some cranes have previously been constructed to move like trailers when pulled by another vehicle. However, lack of stability, difficulty in maneuvering, complexity in construction, and the need for time consuming steps to reconfigure such devices between their crane and trailer configurations are among numerous problems common to such prior designs.
Cranes have often been inadequate for moving loads under battlefield conditions. Lack of sufficient reliability and inability to withstand nearby explosions are among factors which hinder the use of cranes to move materials in support of Army field operations.